Flame retardant polycarbonate composition

ABSTRACT

A flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of heterocyclic sulfonic acids.

United States Patent m1 Mark [ FLAME RETARDANT POLYCARBONATE COMPOSITION[75] Inventor: Victor Mark, Evansville. Ind.

[73] Assignee: General Electric Company.

Pittsfield, Mass.

[22] Filed: Dec. 28. I973 211 Appl, NO; 429,166

[52] US. Cl... 260/458 N; 260/458 R; 260/458 A;

160/458 SN; 260/458 NZ [5]] Int. CL CO8L 69/00 [581 Field ofSearch260/458 R. 45.8 R8. 458 RW.

260/458 A. 458 N 458 NW, 45.8 NT 458 NZ. 438 SW Nov. 11, 1975 {56]References Cited UNITED STATES PATENTS 3.535JUU IU/I97U Gable l l l v l.INN-$5 8 SN 3.775.367 ll/l973 Nomcrmc ZhUMifi) R Primary blmminerlvl .1Welsh Anal-n0 Agent. or Firm-William F, Mufatti; Donald M. Papuga 8Claims, N0 Drawings FLAME RETARDANT POLYCARBONATE COMPOSITION Thisinvention is directed to a flame retardant polycarbonate composition andin particular an aromatic polycarbonate containing in admixturetherewith a particular flame retardant additive which may be the metalsalts of sulfonic acids of heterocyclic compounds.

BACKGROUND OF THE INVENTION With the increasing concern for safety,there is a positive move towards providing safe materials for public andhousehold use. One particular area of need is that of providing flameresistant or flame retardant products for use by the ultimate consumer.As a result of this demand, many products are being required to meetcertain flame retardant criteria both by local and federal governmentand the manufacturers of such products. One particular set of conditionsemployed as a measuring standard for flame retardancy is set forth inUnder writers Laboratories, Inc. Bulletin 94. This Bulletin sets forthcertain conditions by which materials are rated for self-extinguishingcharacteristics.

in the art, there are many known flame retardant additives which areemployed by mixing with products to render such materialsself-extinguishing or flame retardant. Such flame retardant additiveshave been known to be employed in amounts of 5 to weight percent inorder to be effective in extinguishing burning of those products whichare combustible. It has also been found that such amounts can have adegrading effect upon the base product to be rendered flame retardant,resulting in the losses of valuable physical properties of the baseproduct. This is particularly so when employing known flame retardantadditives with the base product polycarbonate resins. Many of theseknown additives have a degrading effect upon the polymer.

DESCRIPTION OF THE lNVENTlON It has now been surprisingly discoveredthat an aromatic polycarbonate can be made flame retardant byincorporating with the aromatic polycarbonate minor amounts of certainadditives, which additives are inert and do not degrade the aromaticpolycarbonate. The particular additive employed herein is unique in thateven very minor amounts render the aromatic polycarbonate flameretardant. The amount of the additive employed herein can vary,preferably, from 0.01 to about 10 weight percent based on the weight ofthe aromatic polycarbonate.

More specifically, the particular additive of this invention is themetal salt of substituted and unsubstituted sulfonic acid ofheterocyclic compounds and includes mixtures of these. The metal saltemployed in the practice of this invention is either the alkali metal oralkaline earth metal salt or mixtures of these metal salts. The metalsof these groups are sodium, lithium, potassium, rubidium, cesium,beryllium, magnesium, calcium, strontium and barium.

The substituted sulfonic acid of heterocyclic compounds employed in thepractice of this invention is one wherein the substituent is an electronwithdrawing radical. As employed herein and within the scope of thisinvention, any of the electron withdrawing radicals can be employed inthe practice of this invention. However. preferably. the electronwithdrawing radical or substituent employed in the practice of thisinvention is 2 the halo-, nitro-, trihalomethyl and cyano electronwithdrawing radicals or mixtures of these electron withdrawing radicals.

The electron withdrawing phenomenon, or as it is also referred to aselectronegativity, is defined in Basic Principles of Organic Chemistryby Roberts and Caser-io, l964 (pages l-l86), and Physical OrganicChemistry by Jack l-line, McGraw-Hill Book Company, Inc. 1962 (pages 5,32 and 85-93 Briefly, the electron withdrawing phenomenon is where theradical has a strong affinity for a negative charge, namely electrons,but still remains covalent and does not form an ion. This is anextremely brief description of this phenomenon and is merely set forthhere to describe the elec tron withdrawing efi'ect. Reference should bemade to the texts set forth above.

In the practice of this invention, the metal salts of the sulfonic acidsof heterocyclic compounds have the following formula:

o-|s a )i-a wherein X is an electron withdrawing radical. M is a metalwhich may be selected from the periodic table of either an alkali metalor an alkaline earth metal and R is an organic nucleus selected from thegroup of organic heterocyclic nuclei consisting of wherein Z is selectedfrom the hetero atoms consisting of sulfur, oxygen and nitrogen,

wherein Z and Z are independently selected from the group consisting ofcarbon and the hetero atoms, nitrogen, sulfur and oxygen, providing thatat least one 2 is a hetero atom.

wherein Z is selected from the hetero atoms consisting of nitrogen,oxygen and sulfur.

PREFERRED EMBODIMENT OF THE INVENTION In order to more fully and clearlyillustrate the present invention. the following specific examples arepresented. It is intended that the examples be considered asillustrative rather than limiting the invention disclosed and claimedherein. In the examples, all parts and percentages are on a weight basisunless otherwise specifled.

EXAMPLE I Ninety-nine (99) parts of an aromatic polycarbonate. preparedby reacting 2.2-bis(4-hydroxyphenyl)propane and phosgene in the presenceof an acid acceptor and a molecular weight regulator and having anintrinsic viscosity of 0.57 is mixed with I part of a finely grounddehydrated additive listed in Table l. by tum- 4 mens. The criteria foreach SE rating per UL-94 is briefly as follows:

SE-O: Average flaming and/or glowing after removal of the igniting flameshall not exceed 5 seconds and none of the specimens shall drip flamingparticles which ignite absorbent cotton.

SE-I: Average flaming and/or glowing after removal of the igniting flameshall not exceed seconds and the glowing does not travel vertically formore than Va inch of the specimen after flaming ceases and glowing isincapable of igniting absorbent cottOl'I.

SE-Il: Average flaming and/or glowing after removal of the ignitingflame shall not exceed 25 seconds and the specimens drip flamingparticles which ignite absorbent cotton. In addition, a test bar whichcontinues to burn for more than 25 seconds after removal of the ignitingflame is classified, not by UL-94, but by the standards of the instantinvention, as "burns". Further, UL-94 requires that all test bars ineach test group must meet the SE type rating to achieve the particularclassification. Otherwise. the 5 bars receive the rating of the worstsingle bar. For example. if one bar is classified as SE-II and the otherfour (4) are classified as SE-O. then the rating for all 5 bars is SE".

The results of the different additives within the scope of the instantinvention are as follows with a control being the aromatic polycarbonateas prepared above without the additive of the type set forth herein.

TABLE I.

Flame Out Time No. of Drips Addithe I I0 eight percent) Seconds (Aug)Per Test Bar Rating Remarks CONTROL 3 l .6 4+ Burns Disodium thiohene2.5-Llisulfonate 3.3 H] SEII Calcium thiop ene-Z-sulfonate .8 1.6SE" Sodium benLothiophenox-sulfonate 6.0 0.8 SE" I test bar was SE-0Sodium 4 bromolhiophene-l-sulfonate 8.5 1.2 SE" 2 test bars were SE-0Sodium 5-hromothiophene 9.2 0.8 SE-ll 3 test bars were SE-I Sodium4.S-dibromothiophene-2-sulfonate ts 0.4 SE-l Calcium4.5dihromothiophene-2-sulfonate 4.7 0.2 SE-U Sodium2.5-dihromothiophene-3-sulfonate 4.4 0.4 SE-0 Sodium2.4.5-trihromoth|ophene-3-sullonate 4.1 0.8 SE" 2 test bars were SE-0Sodium 2.5-dichlorothiophene-3-sulfonate 4.2 0 SE-0 Calcium2.5-dichlorothiophene-3-sulfonate 4.6 0 SE-(] Sodium pyridine-F-sulfohate 2.2 4.0 Calcium pyridine-3-sull'onate .9 2.0 SE-ll Sodium2.(vdichloropyridine-3-sulfonate 4.7 0.6 SE-Il 2 test bars were SE-(lDisodium indigo-5.5 disult'onute 8.4 L8 SE-ll l test bar was SE-lTetrasodium copperphthalocyaninetetra- 6.4 2.2 SE- sulfonate Disodium2.4.5.7-tetrachlorodibenzothio- 2.8 0 SE-0 hene-Bb-disull'onate isodium2.7-dichlorodihenzofuran[.8- 4.2 0.8 SE4) disulfonate Calcium2-(trifluoromethyl)pyridine-S- 2.9 1.6 SE-ll sulfonate Sodium 4-cyanoyridine-Lsulfonate 7.2 3.0 SE" Sodium 2.5-dichToro-Il-nitrothiophene-4.4 0 SE-(] 4-sulf0nate EXAMPLE II bling the ingredients together in alaboratory tumbler. The resulting mixture is then fed to an extruder,which extruder is operated at about 265C, and the extrudate iscomminuted into pellets.

The pellets are then injection molded at about 3 l 5C. into test bars ofabout 5 in. by V2 in. by about l/I6-Vs in. thick. The test bars (5 foreach additive listed in the Table) are subject to the test procedure setforth in Underwriters Laboratories. Inc. Bulletin UL-94. Burning Testfor Classifying Materials. In accordance with this test procedure.materials so investigated are rated either SE-O. SE-l or SE'II based onthe results of 5 specidure of Example I with the following results;

TABLE 2.

Flame Out Time No. of Drips Addithe 10.01 weight percent) Seconds (Avg)Per Test Bar Rating Remarks CONTROL 31.6 4+ Burns SodiumZ,5-dichlorothiophene B-sulflmate 9.2 3.6 SE-Il Calcium2.S-dibromolhiophenefl-sulfonate l 1.0 1.8 SE-ll Sodium Ifvdichlorop}ridineJ-sult'onate l 1.6 3.9 SE tetrasodium copperphthalocyaninetetral.4.4 SE-[l sulfonate EXAMPLE 111 This Example is set forth to show theeffect of a known commercially available flame retardant additive.

Example I is repeated except that in place of the additives employedtherein, only 1 part l,2,5,6,9,l-hexabromocyclododecane is used herein.The results obtained upon evaluating five test bars are the same asobtained for the Control shown in Table 1. above.

Part A. above is repeated but using 5 weight percent of the aboveadditive, namely 1,2,5,6,9,l0-hexabromocyclododecane. The resultsobtained are the same as obtained in Part A. above.

Part A. above is repeated but using weight percent of the aboveadditive, namely l,2,5,6,9,l0hexabromocyclododecane. At this level ofadditive, test bars are rated SE-ll. However, the polycarbonate is badlydegraded as evidenced by severe dark streaking of the molded test bars,which degradation does not occur with the additives of the instantinvention.

EXAMPLE IV Example 111 is repeated except that hexabromobiphenyl isemployed herein. The results obtained are essentially the same as thoseof Example 111.

EXAMPLE V Example 111 is repeated except that the additive employedherein is a combination of antimony oxide and a material which is amixture of polychlorinated biphenyl (Aroclor by Monsanto Company). Theproportion of the ingredients of the additive employed in this exampleis based on 3 parts of chlorine per l part of antimony. The resultsobtained at 1 weight percent and 5 weight percent amounts are the sameas in Example 111.

However, at the higher amount, namely 10 weight percent, flameretardancy effect is noted with, but again, severe degradation of thepolycarbonate, as evidenced by the substantial reduction in theintrinsic viscosity of the molded test bars. As molded, the intrinsicviscosity of the test bars with 1 weight percent of the above additiveis about 0.50. The intrinsic viscosity of the molded test barscontaining 10 weight percent of the flame retardant additive of thisExample is 0.253. This shows the severe degradation of the polycarbonatewhen employing this type of well known flame retardant.

1n the practice of this invention, aromatic carbonate polymers arerendered flame retardant by the addition of certain particular additiveswhich are the metal salts of substituted and unsubstituted sulfonicacids of heterocyclic compounds and which includes mixtures of thevarious metal salts and the said heterocyclic compounds. The amount ofthe additives employed in the practice of this invention may vary from0.01 to up to that amount which, after further increasing of such anamount, does not materially increase the flame retardant properties ofthe carbonate polymer. This is gen erally up to about 10 weight percentbased on the weight of the aromatic carbonate polymer but may be higher.The amount of the additive to be employed can also be a function of thedegree of flame retardancy desired.

It is not exactly understood how the additive of this inventionfunctions or how such minor amounts can act as an effective flameretardant for the aromatic carbonate polymer. Analysis of thecomposition of this invention after being subjected to a tiretemperature of about 600C. showed an unusually high percentage ofremaining char. This leads one to hypothesize that the additive may actas a cross-linking agent when the aromatic carbonate polymer issubjected to fire temperatures. However, it is emphasized that this isonly theory and should not be construed as actually occurring.

As indicated previously, the additive of the instant invention comprisesthe alkali or alkaline earth metal salts of the substituted andunsubstituted sulfonic acids of heterocyclic compounds and mixturesthereof. While a great number of such salts are set forth in the tablesof the Examples of the instant invention, these are only arepresentative sample of the additives of this invention. The sodium,calcium, magnesium, potassium, strontium, lithium, barium, rubidium andcesium salts of other sulfonic acids of heterocyclic compounds can beemployed in place of those of the Examples with the same effective flameretardancy being achieved. These other metal salts of sulfonic acids ofheterocyclic compounds are:

trifluorothiophenesulfonic acid, calcium saltthianaphtheneindeneindigodisulfonic acid, disodium saltpyridine-3,5-disulfonic acid, dipotassium salttetrachlorodibenzopyrroledisulfonic acid, disodium salttrichloroquinoline-8-sulfonic acid, lithium saltoctachlorocopperphthalocyaninetetrasulfonic tetrasodium salttetrachlorothianthrenedisulfonic acid, barium saltdichlorobenzothiazolesulfonic acid, sodium salt3,4,S-triclorothiophene-2-sulfonic acid, calcium salt3,4-dichlorothiophene-2,5-disulfonic acid, disodium salt In the practiceof this invention, the additive is generally prepared by well knownmethods in the art. For example, one such well known method involvestaking the heterocyclic compound, such as thiophene, and contacting itwith either of the electron withdrawing components such as throughchlorination, bromination or nitration. This is then subjected tosulfonation using acid.

either sulfuric acid. chlorosulfonic acid, fuming sulfonic acid orsulfur trioxide. These reactions can be carried out at room temperatureor at elevated temperatures such as about 50C Alternatively. the orderot the above reaction can be reversed. The salt is then prepared byadding the proper alkaline reagent in sufficient amount to make theneutral salt. The salt is then recovered by precipitation or bydistillation of the solvent.

ln the case of the trihalomethyl electron withdrawing substituent, suchas trifluoromethyl electron withdrawing substituent, it is best to startwith the prepared trifluoromethyl heterocycle and then sulfonate asabove, as well as preparing the salt thereof.

In the case of the cyano-substituent, it is best to prepare the sulfonicacid by oxidation of the corresponding thiophenol by hydrogen peroxideor organic peracids. The salt is then made as above and recoveredaccordingly. This technique is also best for the preparation of sulfonicacids with the trichloromethyl substituent.

ln the practice of this invention, any of the aromatic polycarbonatescan be employed herein. However, particularly useful are the aromaticpolycarbonates prepared by reacting a dihydric phenol, such asbisphenol- A (2,2'bis(4 hydroxyphenyl) propane) with a carbonateprecursor. Typical of some of the dihydric phenols that may be employedin the practice of this invention are bis(4-hydroxyphenyl)methane,2,2-bis(4-hydroxyphenyl) propane, 2,2-bis( 4-hydroxy-3-methylphenyl)-propane, 4.4-bis( 4-hydroxyphenyl )heptane, 2,2- (3,5 ,3 ,5-tetrachloro-4,4 -dihydroxydiphenyl )propane, 2 ,2-( 3 ,5 ,3 ,5'-tetrabromo-4,4 '-dihydroxydiphenyl )propane, (3,3 '-dichloro-4,4'-dihydroxydiphenyl )methane. Other dihydric phenols of the bisphenoltype are also available and are disclosed in US. Pat. Nos. 2,999,835,3,028,365 and 3,334,154.

ln addition, the reaction is carried out with the carbonate precursor inthe presence of a molecular weight regulator, an acid acceptor and acatalyst. The preferred carbonate precursor generally employed inpreparing carbonate polymers is carbonyl chloride. However. othercarbonate precursors may be employed and this includes other carbonylhalides, carbonate esters or haloformates.

The acid acceptors, molecular weight regulators and catalysts employedin the process of preparing polycarbonates are well known in the art andmay be any of those commonly used to prepare polycarbonates.

It will thus be seen that the objects set forth above among those madeapparent from the preceding description are efficiently attained andsince certain changes may be made in carrying out the above process andin the composition set forth without departing from the scope of thisinvention, it is intended that all matters contained in the abovedescription shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

l. A flame retardant aromatic polymer composition comprising inadmixture an aromatic carbonate polymer and a minor amount of anadditive selected from the group consisting of the metal salts ofsubstituted and unsubstituted sulfonic acids of heterocyclic compounds,and mixtures thereof, wherein said metal salts thereof are selected fromthe group consisting of alkali metals and alkaline earth metals, andmixtures of the metal salts, and wherein said substituent on the metalsalt of the substituted sulfonic acids of heterocyclic compounds isselected from the group consisting of an electron withdrawing radicaland mixtures of electron withdrawing radicals; and wherein saidheterocyclic compound is selected from the group consisting of five andsix membered heterocyclic nuclei containing a hetero atom selected fromthe group consisting of nitrogen, oxygen and sulfur.

2. The composition of claim 1 wherein the metal salts of substituted andunsubstituted sulfonic acids of heterocyclic compounds has the followingformula:

ois $03M )l-(v' wherein X is an electron withdrawing radical and M is ametal selected from the group consisting of alkali metal and alkalineearth metal and R is an organic nucleus selected from the group oforganic heterocyelic nuclei consisting of:

wherein Z is selected from the hetero atoms consisting of sulfur, oxygenand nitrogen,

wherein Z and Z are independently selected from the group consisting ofcarbon and the hetero atoms, nitrogen, sulfur and oxygen, providing thatat least one Z is an hetero atom.

D. Phtalocyanine (SO M) tion is sodium 2,5dichlorothiophene-3-sulfonate.

7. The composition of claim 2 wherein the composition is tetrasodiumcopper phthalocyamne tetrasu HIE 8. The composition of claim 2 whereinthe composihloro tion is calcium 2,5-dic thiophene-3-sulfonate.

1. A FLAME RETARDANT AROMATIC POLYMER COMPOSITION COMPRISING INADMIXTURE AN AROMATIC CARBONATE POLYMER AND A MINOR AMOUNT OF ANADDITIVE SELECTED FROM THE GROUP CONSISTIING OF THE METAL SALTS OFSUBSTITUTED AND UNSUBSTITUTED SULFONIC ACIDS OF HETEROCYCLIC COMPOUNDS,AND MIXTURES THEREOF, WHEREIN SAID METAL SALTS THEREOF ARE SELECTED FROMTHE GROUP CONSISTING OF ALKALI METALS AND ALKALINE EARTH METALS, ANDMIXTURES OF THE METAL SALTS, AND WHEREIN SAID SUBSTITUENT ON THE METALSALT OF THE SUBSTITUTED SULFONIC ACIDS OF HETEROCYCLIC COMPOUNDS ISSELECTED FROM THE GROUP CONSISTING OF AN ELECTRON WITHDRAWING RADICALAND MIXTURES OF ELECTRON WITHDRAWING RADICALS, AND WHEREIN SAIDHETEROCYCLIC COMPPUND IS SELECTED FROM THE GROUP CONSISTING OF FIVE ANDSIX MEMBERED HETEROCYCLIC NUCLEI CONTAINING A HETERO ATOM SELECTED FROMTHE GORUP CONSISTING OF NITROGEN, OXYGEN, AND SULFUR.
 2. The compositionof claim 1 wherein the metal salts of substituted and unsubstitutedsulfonic acids of heterocyclic compounds has the following formula: XO15R(SO3M)1 6 wherein X is an electron withdrawing radical and M is ametal selected from the group consisting of alkali metal and alkalineearth metal and R is an organic nucleus selected from the group oforganic heterocyclic nuclei consisting of:
 3. The composition of claim 1wherein the electron withdrawing radical is selected from the groupconsisting of halo-, nitro-, trihalomethyl- and cyano- radicals, andmixtures thereof.
 4. The composition of claim 2 wherein the compositionis sodium 2,5-dichlorothiophene-3-sulfonate.
 5. The composition of claim2 wherein the composition is sodium 2,6-dichloropyridine-3-sulfonate. 6.The composition of claim 2 wherein the composition is disodiumindigo-5,5''-disulfonate.
 7. The composition of claim 2 wherein thecomposition is tetrasodium copper phthalocyanine tetrasulfonate.
 8. Thecomposition of claim 2 wherein the composition is calcium2,5-dichlorothiophene-3-sulfonate.